Newbie Mining rig with R9 290 Tri x

[drdops]

i just got 15 x sapphire r9 290 tri x and was going to do 5 rigs with win 7..now i think ill try 3 rigs with 5 cards..
i already have 3x Gigabyte 990XA-UD3 AMD 990X (Socket AM3+) DDR3 Motherboard  and 3x Silverstone SST-ST1200-G Strider Evolution Gold Series - 1200 Watt

could i run 5 cards on this mobo in win 7? how much extra power would i need for each rig? would i run 3 or 4 cards off the 1200w?- and the remaining cards and mobo off the additional psu.
could you tell me exactly what else i need to make it work..ie specific power risers, things to connect psu's etc.. (Its my first build- so will need it spelled out)

Would a 1600w psu power 5 cards and the above mobo with risers?

Does my mobo need powered risers?- does the speed of the pcie slots matter?

Do the psu's use only the minimum power required? or should i get the least wattage i require to minimise costs of electricity?

Is it safe to plug multiple psu's on an extension lead into a single 220v mains socket?
How do i get all the rigs to output to one monitor?
Any other tips for safety and cost reduction?

thanks

[szwagier]

I dont think it will be possible to run 5 gpu on windows without  BSODs and other problems

[johnnicholss]

how many gpu's windows can run? i am planning to buy 3 9770 and put it n one machine it is possible?